Switched-mode power converters include direct current (“DC”)-DC, DC-alternating current (“AC”), AC-DC, and AC-AC configurations. DC-DC switched-mode power converters are often used to provide regulated power to electrical loads in, for example, microelectronic devices. Prior art voltage regulators are generally configured to maintain the voltage, supplied to a dynamic load, at a nominal operating load voltage. Typical prior art voltage regulators (e.g., a switching regulator) may be effective in tracking the slow power changes in the dynamic load; however, the voltage regulators may not be able to suitably track fast changes. During operation of a dynamic load, transient power events may occur. If adjustments to such transient events are not rapidly made, the load may experience dips or spikes in the voltage, which may in turn deleteriously affect the performance of the load.
With reference now to FIG. 1, a typical prior art voltage regulator may comprise a switched-mode power converter 100 and a switched-mode controller 120. Switched-mode power converter (“SMPC”) 100 may comprise passive components, such as inductors L, capacitors C, or transformers. SMPC 100 may also comprise power semiconductor devices operated as switches, such as transistors Qj and Qk. These transistors may be controlled by logic-level on/off signals c. SMPC 100 is configured to receive power from a supply voltage Vg at its input, and to provide a regulated voltage signal at its output to a load 110. Typically, the output voltage is sensed and the sensed output voltage Hvout is compared to a reference voltage Vref to generate an error signal ve.
In some prior art SMPC's, tight regulation of the output voltages or currents is accomplished through a feedback mechanism comprising a switched-mode controller 120. For example, switched-mode controller 120 is configured to receive the error signal ve and generate one or more logic level control signals c that determine the on/off states of the power semiconductor switches.
Many well-known techniques are available to design and construct switched-mode controllers. For example, in a constant-frequency pulse-width modulation (PWM) controller, the switch control signals have constant frequency equal to the switching frequency, while the signal duty ratio or phase is adjusted to regulate the output voltage. Other well-known approaches include current-mode controllers, hysteretic controllers, sliding-mode controllers, controllers based on pulse-frequency modulation, or controllers based on a combination of these techniques. Switched-mode controllers can be realized using analog, digital or mixed signal circuits.
Unfortunately, although many of these techniques are able to achieve precise and tight regulation in steady state operation, dynamic responses to large-signal disturbances are often significantly worse than desired. These large-signal disturbances may arise due to fluctuations in input power or load disturbances. Moreover, in digital controller implementations, dynamic responses are further affected by delays in the control loop, and by quantization effects due to finite resolutions of analog-to-digital (A/D) converters, digital pulse-width modulators, and internal computations. Thus, typical prior art switched-mode power regulator (converter/controller) systems often do not achieve desired stability and precise regulation under transient conditions. Therefore, there is a need to improve large-signal dynamic response of closed-loop switched-mode power regulators, while preserving precise regulation and wide small-signal stability margins achieved by standard switched-mode regulators.